Direct Liquid Phase Exfoliation of Graphite to Produce Few-Layer Graphene by Microfluidization.

Graphene has attracted a great number of attentions due to the excellent physical and chemical properties. For the convenience of investigations and applications, it is crucial to produce the grapheme with high-quality and high-yield by an easy-obtained method. In this research, a promising method is demonstrated to produce a high-concentration few-layer graphene (FLG) dispersion by direct microfluidization in water/surfactant systems. The effects of surfactant selection, chamber pressure and microfluidization cycles on the graphitic material exfoliation efficiency are systematically studied. The FLG concentration and the quality of the as-prepared FLG were determined by a series of characterizations. The graphene dispersions, with an average lateral size of 0.6 µm and a few-layer structure, were stabilized by surfactants at a high concentration of up to 1.7 mg/mL and exhibited a relatively high quality (ID/IG = 0.07-0.56, C/O ~ 19.36) within a processing time of a few hours. This method should facilitate the mass production of high-quality graphene by liquid-phase exfoliation and promote the industrial application of graphene.

Homogeneous synthesis of cellulose acrylate-g-poly (n-alkyl acrylate) solid-solid phase change materials via free radical polymerization.

A novel solid-solid phase change materials, namely, cellulose acrylate-g-poly (n-alkyl acrylate) (CA-g-PAn) (n = 14, 16 and 18) were successfully synthesized by free radical polymerization in N, N-dimethylacetamide (DMAc). The successful grafting was confirmed by fourier transform infrared spectra (FT-IR) and nuclear magnetic resonance (NMR). The properties of the CA-g-PAn copolymers were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). The phase change temperatures and the melting enthalpies of CA-g-PAn copolymers are in the range of 10.1-53.2 °C and 15-95 J/g, respectively. It can be adjusted by the contents of poly (n-alkyl acrylate) and the length of alkyl side-chain. The thermal resistant temperatures of CA-g-PA14, 16 and 18 copolymers are 308 °C, 292 °C and 273 °C, respectively. It show that all of grafting materials exhibit good thermal stability and shape stability. Therefore, it is expected to be applied in the cellulose-based thermos-regulating field.

MnO2/MWCNTs Nanocomposites as Highly Efficient Catalyst for Indoor Formaldehyde Removal.

Formaldehyde (HCHO) is a main indoor pollutant that is capable of harming the health of residents. Here, we fabricated a novel MnO2/MWCNTs nanocomposite film for non-photocatalytic, room temperature removal of indoor HCHO. MnO2/MWCNTs nanocomposites with various amounts of a-MWCNTs, which were fabricated by a co-precipitation method, were assembled into composite films using vacuum filtration and solvent evaporation. Structural analysis confirms that MnO2 nanoparticles are homogeneously distributed on a-MWCNTs. The acetyl acetone method was used to characterize the catalytic activity of MnO2/MWCNTs nanocomposites. The results show that MnO2/MWCNTs composites with 30 wt% a-MWCNTs present the highest catalytic activity due to a highly active surface. The catalytic activity of MnO2/MWCNTs composite film was characterized in a glovebox at room temperature and showed good removal of HCHO. This study suggests that supporting catalysts on MWCNTs and then assembling them into fibers (1D), films (2D) or aerogels (3D) is a worthwhile approach to promote catalytic activity and prevent dust pollution.

Immunosuppressive sesquiterpenes from Buddleja daviddi.

Six new sesquiterpenes, 2,6(12),10-humulatrien-7ß-ol-1-one (1), 2 α-acetoxy-5α-methoxy-enantio-caryophylla-8(15)-en-3-one (2), 2α-acetoxy-5α-hydroxy-enantio-caryophylla-8(15)-en-3-one (3), 2α-acetoxy-4ß,5α-hydroxy-enantio-caryophylla-8(15)-en-3-one ( 4), 2α-acetoxy-4ß,5ß-hydroxy-enantio-caryophylla-8(15)-en-3-one (5), 2ß-acetoxy-4-caryophyllen-8ß-ol-3-one (6), and nineteen known compounds were isolated from the ethanol extract of Buddleja daviddi. The structures were elucidated by spectroscopic methods. Compounds 8-11, 14, 16, 17, and 20 showed significant immunosuppressive activities, and 8-11 and 14 were cytotoxic on HeLa and L929 cell lines.

Crystallization and prevention of supercooling of microencapsulated n-alkanes.

Microencapsulated n-alkanes (n-octadecane, n-nonadecane, and n-eicosane) were synthesized by in situ polymerization using urea-melamine-formaldehyde polymer as shells. Microcapsules 5.0 and 10.0 wt% of 1-tetradecanol, paraffin, and 1-octadecanol were used as nucleating agents. The fabrication was characterized using Fourier transform infrared, light microscopy, and scanning electron microscopy. The crystallization and prevention of supercooling of the microcapsules are studied using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction. The crystal system of the microencapsulated n-alkane is the same as that of the bulk. The enthalpies of the microcapsules containing 70 wt% n-alkanes are approximately 160 J/g. The melting temperature of the n-alkanes in the microcapsule is the same as that in the bulk. There are multiple peaks on the DSC cooling curves that are attributed to liquid-rotator, rotator-crystal, and liquid-crystal transitions. The DSC cooling behavior of microencapsulated n-octadecane is affected by the average diameters. The measured maximum degree of supercooling of the microencapsulated n-octadecane is approximately 26.0 degrees C at a heating and cooling rate of 10.0 degrees C/min. The degree of supercooling of microencapsulated n-octadecane is decreased by adding 10.0 wt% of 1-octadecanol as a nucleating agent.